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Optimum thickness of Mssbauer absorber

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Nuclear Science and Techniques 2000年第2期11卷 91-95页

作者： CHEN yi-Long yi Fan, zhang fu-Liang(Department of Physics of Wuhan University,Wuhan 430072) 武汉大学湖北武汉武汉大学湖北武汉 430072

If recoilless fraction fa is available, the optimum absorber thickness dopt can be calculated by maximizing the signal to noise ratio or Q factor. In this work,an approach presented is to get experimental Qexp as a function of the thickness,andthen fitting Qexp by its theoretical expression gives fa value. At last the dopt value is deduced from a maximum on the fitted *** such a way, thicknesses of six specimens with quadrupole or magnetic hyperfinc splitting were optimized.

关键词：穆斯堡尔光谱穆斯保尔效应信噪比最佳吸收厚度噪声光谱吸收

Cavitation vortex dynamics of unsteady sheet/cloud cavitating flows with shock wave using different vortex identification methods

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Journal of Hydrodynamics 2019年第3期31卷 475-494页

作者： Chang-chang Wang ying Liu Jie Chen fu-yi zhang Biao Huang Guo-yu Wang School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China

Cavitation is a complex multiphase flow phenomenon with an abrupt transient phase change between the liquid and the vapor, including multiscale vortical motions. The transient cavitation dynamics is closely associated with the evolution of the cavitation vortex structures. The present paper investigates the cavitation vortex dynamics using different vortex identification methods, including the vorticity method, the Q criterion method, the Omega method (Ω), the method and the Rortex method. The Q criterion is an eigenvalue-based criterion, and in the Ω method, the parameter is normalized, is independent of the threshold value and in most conditions Ω= 0.52 . The Rortex method is based on an eigenvector-based criterion. Numerical simulations are conducted using the implemented compressible cavitation solver in the open source software OpenFOAM for the sheet/cloud cavitating flows around a NACA66 (mod) hydrofoil fixed at a = 6°,= 1.25 and Re = 7.96 × 10^5 . The flow is characterized by the alternate interactions of the re-entrant flow and the collapse induced shock wave. Results include the vapor structures and the vortex dynamics in the unsteady sheet/cloud cavitating flows, with emphasis on the vortex structures in thecavitation region, the cavity interface, the cavity closure, the cavity wakes, and the foil wakes with the shedding cavity. The comparisons of the various methods, including that the vorticity method, the Q criterion method, the Ω method, the λ2 method and the Rortex method, show the performances of different methods in identifying the cavitation vortex structures. Generally, during the attached cavity growth stage, the Q criteria can well predict the vortex structures in the cavitation region and at the foil trailing edge in the pure liquid region, while with the Ω method and the Rortex method, the vortex structures outside the attached cavity and on the foil pressure side can also be predicted. The λ2 method can well predict the vortex structures in t

关键词： Cavitation vortex dynamics vortex identification sheet/cloud cavitating flow re-entrant jet shock wave OpenFOAM

A New Autoxidation-Michael Addition of a Glycoside Lactone Derivative

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有机化学 2003年第Z1期23卷 368-369页

作者： zhang fu-yi zhang Jian-Ye HUANG Li-Hua TAO Jing-Chao LIU Hong-Min Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052 Department of Chemistry Zhengzhou University Zhengzhou 450052

　　C-branched chain glycopyranosiduloses are very efficient chiral building blocks for synthesis of biologically active substances, containing carbocyclic ring systems. Synthesis of such type of structural units has ... 详细信息

关键词： active substances building blocks type of

Bistable switch molecule DPACdCl_(4) showing four physical channels and high phase transition temperature

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Chinese Chemical Letters 2025年第1期36卷 591-596页

作者： ying-Yu zhang Jia-Qi Luo Yan Han Wan-ying zhang yi zhang Hai-Feng Lu Da-Wei fu Institute for Science and Applications of Molecular Ferroelectrics Key Laboratory of the Ministry of Education for Advanced Catalysis MaterialsZhejiang Normal UniversityJinhua 321004China Ordered Matter Science Research Center Jiangsu Key Laboratory for Science and applications of Molecular FerroelectricsSoutheast UniversityNanjing 211189China

Multiple switchable physical channels within one material or device,encompassing optical,electrical,thermal,and mechanical pathways,can enable multifunctionality in mechanical-thermal-opto-electronic *** integrated encryption and enhanced performance in storage and sensing presents a formidable challenge in the synthesis and functionality of new *** an effort to overcome the complexities associated with these multiple physical functions,this study investigates the large-size crystal of DPACdCl_(4)(DPA=diisopropylammonium),revealing significant features in rare multi-channel *** compound demonstrates the ability to switch between"OFF/0"and"ON/1"states in the mechanical-thermal-opto-electronic ***,DPACd Cl_(4)possesses four switchable physical channels,characterized by a higher phase transition temperature of 440.7 K and a competitive piezo-electric coefficient of 46 pC/***,solid-state NMR analysis indicates that thermally activated molecular vibrations significantly contribute to its multifunctional switching capabilities.

关键词： Organic-inorganic hybrid Phase transition Crystal Perovskite Piezoelectricity

Self-assembly of two pairs of homochiral M2L4 coordination capsules with varied confined space using Tr?ger's base ligands

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Chinese Chemical Letters 2025年第2期36卷 360-365页

作者： yi Zhou Wei zhang Rong fu Jiaxin Dong Yuxuan Liu Zihang Song Han Han Kang Cai College of Chemistry Nankai University Department of Chemistry Northwestern University Department of Chemistry The University of Hong Kong

Chiral coordination molecular cages/capsules with discrete nanoconfined chiral cavities demonstrate significant potential applications across various fields. In this study, we utilized Tr?ger's base as the building block to design and synthesize two pairs of enantiopure ligands. These ligands were then self-assembled with Pd(II) ions through chiral self-sorting coordination, resulting in the formation of two pairs of homochiral M2L4-type coordination molecular capsules. Notably, due to differences in the substitution positions on the Tr?ger's base, these two pairs of enantiomeric coordination molecular capsules exhibited distinct levels of cavity closures, cavity sizes, and host-guest recognition properties. This research offers valuable insights into the construction of novel chiral molecular capsules and the regulation of confined cavities.

关键词： Chirality Host-guest recognition Metal-organic capsule Self-sorting Tröger's base

Emission control status and future perspectives of diesel trucks in China

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Journal of Environmental Sciences 2025年第2期148卷 702-713页

作者： Shihai zhang Mingliang fu Hefeng zhang Hang yin Yan Ding State Environmental Protection Key Laboratory of Vehicle Emission Control and Simulation Chinese Research Academy of Environmental SciencesBeijing 100012China Vehicle Emission Control Center Chinese Research Academy of Environmental SciencesBeijing 100012China

Chinese diesel trucks are the main contributors to NOx and particulate matter(PM)vehicle *** increase in diesel trucks could aggravate air pollution and damage human *** Chinese government has recently implemented a series of emission control technologies andmeasures for air quality *** paper summarizes recent control technologies and measures for diesel truck emissions in China and introduces the comprehensive application of control technologies and measures in Beijing-Tianjin-Hebei and surrounding *** onlinemonitoring technology has been adopted according to the China VI standard for heavy-duty diesel trucks,and control measures such as transportation structure adjustment and heavy pollution enterprise classification control continue to support the battle action plan for pollution *** and suggestions are provided for promoting pollution control and supervision of diesel truck emissions:adhere to the concept of overall management and control,vigorously promote the application of systematic and technological means in emission monitoring,continuously facilitate cargo transportation structure adjustment and promote new energy freight *** paper aims to accelerate the implementation of control technologies and measures throughout *** is endeavouring to control diesel truck exhaust *** is willing to cooperate with the world to protect the global ecological environment.

关键词： Air quality Diesel truck emissions Emission control technology Control measures

Riemann-Hilbert Problem and Multiple High-order Poles Solutions of the Focusing mKdV Equation with Nonzero Boundary Conditions

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Acta Mathematicae Applicatae Sinica 2025年第1期41卷 234-251页

作者： Zi-yi WANG Shou-fu TIAN Jin-jie YANG School of Mathematics China University of Mining and TechnologyXuzhou 221116China

The focusing modified Korteweg-de Vries(mKdV)equation with multiple high-order poles under the nonzero boundary conditions is first investigated via developing a Riemann-Hilbert(RH)*** begin with the asymptotic property,symmetry and analyticity of the Jost solutions,and successfully construct the RH problem of the focusing mKdV *** solve the RH problem when 1/S_(11)(k)has a single highorder pole and multiple high-order ***,we derive the soliton solutions of the focusing mKdV equation which corresponding with a single high-order pole and multiple high-order poles,***,the dynamics of one-and two-soliton solutions are graphically discussed.

关键词： Riemann-Hilbert approach focusing mKdV equation nonzero boundary conditions multiple high-order poles soliton solutions

Partial multi-label learning via label-specific feature corrections

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Science China(Information Sciences) 2025年第03期68卷 95-109页

作者： Jun-yi HANG Min-Ling zhang School of Computer Science and Engineering Southeast University Key Laboratory of Computer Network and Information Integration(Southeast University) Ministry of Education

Partial multi-label learning（PML） allows learning from rich-semantic objects with inaccurate annotations, where a set of candidate labels are assigned to each training example but only some of them are valid. Existing approaches rely on disambiguation to tackle the PML problem, which aims to correct noisy candidate labels by recovering the ground-truth labeling information ahead of prediction model induction. However, this dominant strategy might be suboptimal as it usually needs extra assumptions that cannot be fully satisfied in real-world scenarios. Instead of label correction, we investigate another strategy to tackle the PML problem, where the potential ambiguity in PML data is eliminated by correcting instance features in a label-specific manner. Accordingly, a simple yet effective approach named PASE, i.e., partial multi-label learning via label-specific feature corrections, is proposed. Under a meta-learning framework, PASElearns to exert label-specific feature corrections so that potential ambiguity specific to each class label can be eliminated and the desired prediction model can be induced on these corrected instance features with the provided candidate labels. Comprehensive experiments on a wide range of synthetic and real-world data sets validate the effectiveness of the proposed approach.

关键词： machine learning multi-label learning partial multi-label learning label-specific features feature correction

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General synthesis of a dual-atomic-site catalyst library

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Science China Materials 2025年第2期68卷 679-680页

作者： Jingfang zhang yi Huang School of Chemical Engineering&Pharmacy Wuhan Institute of TechnologyWuhan 430205China College of Chemistry Central China Normal UniversityWuhan 430079China

Single-atom catalysts(SACs),as a bridge between homogeneous and heterogeneous catalysts,have attracted tremendous attention over the past *** atomically dispersed metal active sites,SACs possess maximum atom utilization efficiency and exceptionally high activity towards various catalytic reactions[1].Compared with their nanoparticle counterparts,the unique but uniform configurations of the catalytic sites endow SACs with great potential for mechanism investigation at the atomic level[2,3].Despite of these advantages,SACs are facing the problem of linear scaling relations between intermediates in terms of complicated reactions involving co-adsorption of *** is difficult for a single-atom site to participate in all catalytic steps with high efficiencies,especially for some reactions that need adjacent active sites[4].In this regard,dualatomic-site catalysts(DACs)are emerging as a fascinating frontier in heterogeneous catalysis[5].It has been verified that the synergistic effect of the adjacent atomic pairs in DACs can break the linear scaling relations and optimize the adsorption energy of different intermediates,thus improving the intrinsic catalytic ***,it is of great significance to develop a general synthetic strategy for DACs.

关键词： atomic adsorption synthesis